Burner elevation control system



Sept. 12, 1967 J. A. SCHUSS BURNER ELEVATION CONTROL SYSTEM 4 Sheets-Sheet 1 Filed Aug. 31, 1965 D 7 4' w/ I M E D D D 2 A w 4 u 6 3 E l L 1 FT 0 O o U T 3 3 U N Z 0 C 8 a m M v. O 2 4 8 4 I 2 I 1. F u 00000000000000 H u 0 O O m F 7 v H H Q llll- 4 )1 m ,m" 4 EL 8 6 M of m mm 2 [M 3 M" MN I 4 m l A0 H 50 i aw y |H T I!!! 0 111 111 s 4 A 2 0 m I I l 4 2 N 1 F m 2 T R WT M me C INVENTOR 44 BY JACK A. SCHUSS 'ATTORNEY FIG p 1967 .1. A. SCHUSS 3,341,118

BURNER ELEVATION CONTROL SYSTEM Filed Aug. 31, 1965 v 4 Sheets-Sheet 2 i 1 52 1 BOILER III i ,TRIP I l I cw c Q9? 3 c 48 so 4s 1 Q Q G 1 Q5 42 1 42 1 0 U STEAM COMBUSTION 2 42 PRESSURE CONTROL 12 CONTROL\ 1 Q 0 6 '8 E e H FIG. 3

9e IOS-III. 114-1 ll6-IlI I06-III 1114-11 114-111 Luca-1r :H2-'I (lO8-11I rlO8-1I l06-I 66f 68 94 I 554 I36 I38 96/ I '52 '54 FIG. 6 FIG 7 INVENTOR.

JACK A. SCHUSS Sept. 12, 1967 J. A. SCHUSS 3,341,118

BURNER ELEVATION CONTROL SYSTEM Filed Aug. 31, 1965 4 Sheets-Sheet 5 NUMBER OF GUNS IN SERVICE OIL PRESS. PSIG b MINIMUM PRESS.

OIL GUN DISCH. GPM

FIG. 5'

0-5 sec.

START IGNITERS' 5-25 sec BURNER PAIR A-G IIZAIIITZI I BURNER PAIR B-F SEC.

8 BURNER .PAIR C-E 45 SEC.

65- SEC.

BURNER PAIR D- H SEC-RESET MAKE COUNTING CIRCUIT SEQ-RESET MAKE RELAY I02 INVENTOR.

JACK A. SCHUSS FIG. 9 A BY ATTORN Sept. 12, 1967 Filed Aug. 31, 1965 ELEVATION I 4 Sheets-Sheet 4 H Isa-1 ELEVATION 11 ELEVATION m W W A ML w w N I26 I44 m 29319 21 1 A We V54 [Has-1r Mas-II H lee-1: l86-]]I 462i k #138 56% 200 -202 204 Lass L 208Lr FIG. IO INVENTOR.

J'ACK A. SCHUSS BY yam/J ATTORNEY a United States Patent 3,341,118 BURNER ELEVATION CONTROL SYSTEM Jack A. Sclluss, Hartford, Conn., assignor to Combustion Engineering, Inc., Windsor, Conn., a corporation of Delaware Filed Aug. 31, 1965, Ser. No. 484,061 34- Claims. (Cl. 236-26) The present invention relates to fuel firing systems for vapor generators. More particularly, the invention relates to means for automatically placing the burners in a multiburner fuel firing system of a large capacity vapor generator in service in response to changing load demand requirements.

In recent years it has become accepted practice to operate the fuel firing equipment for thermal power stations from a central control room where the various control elements, including gauges, indicating lights, recorders and control switches, etc., are assembled for the plant operators use. The duty of decision making and operation of the control switches, however, remained with the operator to be observed and operated through changing load requirements of the unit. With the increasing size of generating stations the operator has found it more difiicult to cope with the multitude of control equipment necessary for safe, efiicient vapor generator operation. There is a growing demand, therefore, for fuel firing automation to relieve the operators burden and to insure plant safety. It is to this end that the present invention is directed.

Vapor generators with which the present invention is contemplated for use are large capacity units wherein the firing system comprises a plurality of oil or gas fired burners. These units are commonly constructed with burning chambers in the form of divided furnace cavities into which a plurality of burners arranged in groups at various furnace elevations are adapted to fire. The present invention provides means for automatically starting up each of the burners and their ancillary components for such a vapor generator firing system and for controlling the addition of increasing fire power in response to increasing load demand on the unit. By means of the invention there is provided means for automatically determining which of a number of burner elevations are in operation when an increase in load demand occurs and which of the others are capable of being placed in service in order to satisfy the demand. The invention provides means for automatically placing the available or more desirable burner elevation in service.

It is therefore one of the objects of the invention to provide means for automatically overseeing the operation of a large capacity vapor generator through increasing load swings and for placing additional burner elevations in service in response to these load swings.

Another object of the invention is to provide a burner control system that is capable of safely and efliciently operating groups of burners in a multi-burner firing system without the need of operator supervision.

Other and further objects of the invention will become apparent to those skilled in the art as the description proceeds.

With the aforementioned objects in view, the invention comprises an arrangement, construction and combination of the elements of the inventive organization in such a manner as to attain the results desired as hereinafter more particularly set forth in the following detailed description of an illustrative embodiment, said embodiment being shown by the accompanying drawings wherein:

FIG. 1 represents a schematic illustration of a power plant utilizing the present invention;

FIG. 2 is a section taken along line 22 of FIG. 1 illustrating the arrangement of burners in a typical burner elevation;

3,341,118 Patented Sept. 12, 1967 FIG. 3 is a piping diagram illustrating the fuel supply system for the vapor generator;

FIG. 4 is a piping diagram illustrating the fuel supply at each individual burner in the firing system;

FIG. 5 is a graph illustrating the oil discharge curves of a typical power plant operating in accordance with the invention;

FIG. 6 is the master control circuit utilized for placing a second burner elevation in service;

FIG. 7 is the master control circuit utilized for placing the third burner elevation in service;

FIG. 8 is the elevation selection control circuit;

FIG. 9 is a schematic representation of a typical timing device employed for placing the burners of a burner elevation in service;

FIG. 10 is a typical burner counting circuit; and

FIG. 11 is a typical elevation feedback circuit.

Referring now to the drawings, FIG. 1 illustrates a thermal power plant 10 that is operated in accordance with the teachings of the present invention. It comprises a vapor generator 12, a turbine 14 coupled to an electric generator 15 and operatively connected to the vapor generator. Analog controls in the form of an output controller 16, a vapor pressure controller 18 and a combustion controller 20 are employed to control the output of the power plant. The output controller 16 is adapted to sense changing demand requirements on the turbine 14 as received from the load demand controller 17 for altering the input to the turbine 14 in response to these changes. The vapor pressure controller 18 and combustion controller 20 are operative to eifect changes in the liquid and fuel inputs to the vapor generator 12 in order to satisfy the increased input to the turbine. The analog controls 16, 17, 18 and 20 are of known construction and do not form a part of the invention.

The vapor generator 12 is shown as having two furnace cavities 22 and 24 which may be considered as having outer walls lined with vapor generating and wall cooling tubes 26. The cavities 22 and 24 include a common Wall or partition 28 formed of similar tubes. The tubes 26 lining the outer walls of the furnace cavities as well as those of the partition 28 are connected at their lower ends to headers 30 that supply the tubes with vaporizable liquid. At their upper ends the tubes connect to headers 32 that, in turn, are connected to a vapor collecting manifold 34. Vapor is supplied to the turbine 14 through a supply line 36 that contains a vapor regulator valve 38 operated by the output controller 16. A vapor pressure sensor 40 is also positioned in the line 36 and operates to send a feedback signal to the vapor pressure controller 18 in response to vapor pressure changes in the supply line.

A firing system comprising burners 42 here shown as being oil operated is arranged to flow into the furnace cavities 22 and 24. These burners 42 are arranged in groups of eight burners each located at various furnace elevations indicated as I, II and HI. As shown best in FIG. 2, the burners 42 in each elevation along with their associated igniters 44 are located at the corners of the furnace cavities 22 and 24 and so oriented within the cavities as to effect tangential firing. For the sake of clarity the corners of the cavity 22 are indicated as A, B, C and D while those in cavity 24 are indicated as E, F, G and H. Each elevation I, II and III of burners 42 is equipped with its own burner operating control, as hereinafter more full described, so that the elevation can be individually or cumulatively fired depending on the load requirements of the unit.

FIG. 3 illustrates the main fuel supply system for the burner 42. It comprises a main fuel line 46 that is connected in common with all of the burners 42 in each elevation I, II and III. Interposed in the line 46 is a manual shut-off valve 48 and a power operated shut-off valve 50. The power operated shut-off valve 50 has associated therewith a boiler trip control 52 of known construction that is operable to immediately close the valve 50 upon the occasion of an unsafe furnace condition as hereinafter more fully explained. Also interposed in the line 46 is a fuel regulating valve 54 that is adapted to regulate the amount of fuel delivered to the burners 42 in response to the combustion control apparatus 20. Fuel flow through the line 46 is determined by a flow sensor 56 whose signal operates as a feedback to the combustion control apparatus 20. As shown in FIG. 3 a bypass flow regulator 58 operates in conjunction with the fuel regulating valve 54. The purpose of the bypass regulator 58 is to insure the presence of the minimum fuel pressure required for fuel atomization in the burners 42. Therefore, regardless of the fuel pressure called for by the fuel regulator valve 54, the pressure in line 46 can never fall below that required to effect fuel atomization in the burners, which, in the instant arrangement, has been determined to be approximately 100 p.s.i. Also positioned in the line 46 are three pressure sensing elements 60, 62 and 64. The element 60 is operatively connected to the boiler trip controller 52 to operate the controller when a minimum predetermined pressure is found to exist in the line 46. In the present arrangement the sensor 60 is set to operate the controller 52 to terminate operation of the burner system when the fuel pressure in line 46 falls below approximately 90 p.s.i. Each of the pressure sensors 62 and 64 are associated with various control circuits required by the present invention with sensor 62 being associated with the pressure switch having contact 66 that is set to be closed when a pressure of 800 p.s.i. is experienced in the line 46 and sensor 64 being associated with a pressure switch whose contact 68 is set to close when a pressure of 485 p.s.i. is experienced in the line 46.

In FIG. 4 of the drawings there is shown schematically an arrangement that is typical for each burner 42 employed in the system and its associated igniter 44. As shown, the burner 42 is operatively connected to the main fuel supply line 46 by a conduit 70. Valves 72 and 74 are interposed in the conduit 70 for initiating or terminating the admission of fuel to the burners 42, valve 72 being manually operated and valve 74 being a power operated valve having an operator that must be energized to open the valve anad energized also to close the valve. The valve 74 is such that once opened it will remain open until such time as its operator is electrically actuated to close the valve. A normally open limit switch having contact 76 is associated with the power operated valve 74 such that the contact is adapted to be closed when the valve is fully open. Closure of this contact 76 actuates a relay 80 to open its associated normally closed contacts 82, 84 and 86. The operator of the valve 74 also has associated therewith a contact 88 the closure of which effects actuation of the valve to an open position and another contact 90 the closure of which effects actuation of the valve to a closed position. The ignitor 44 associated with each burner 42 is connected to a fuel source (not shown) and has an operator that is actuated upon closure of contact 92 to produce operation of the igniter, which, in turn, ignites the fuel that issues from burner 42.

Referring now to FIGS. 6 and 7 there are shown the master control circuits 94 and 96 operative to place the second and third burner elevations in service when the need for additional heat arises. It is the function of these circuits to determine that a need for additional heat has arisen and how many burner elevations are currently in service to supply the heat. After making such a determination the circuits are responsible for emitting a pulsed signal for starting up the additional burner elevation in a preferred sequence but also in alternate sequences should the preferred sequence not be possible. These circuits each comprise a plurality of contacts associated with various system components and arranged in series-parallel relation across live and ground leads of a 115 volt, 60 cycle, single phase source of electric power. As shown, the circuit 94 which is responsible for placing a second burner elevation in service comprises contacts 98 and 66 connected in series with parallelly arranged contacts of an elevation counting circuit. Contact 98 is associated with a selector switch on the board and is manually operated to place the control system in operation. Contact 66 is that which is associated with the pressure switch operated by pressure sensor 62 in the main fuel line 46 (FIG. 3) for sensing a pressure of 800 p.s.i. In series with these contacts are the contacts that are actuated to determine that any one elevation of burners 42 is currently in service and that any two burner elevations are not in service. To accomplish this function the contacts are each actuated when the burner elevation with which the respective contacts are associated is determined as being in operation. Such determination i made by the elevation feedback circuit 100 shown in FIG. 11 which is simply a series connection of two contacts, the closure of which actuates a relay 102. There are three such circuits in the system, one for each elevation. The relay 102 has associated therewith four normally closed contacts 104, 106, 108 and 110 that are opened when the elevation with which the respective circuits 100 are associated is in operation and five normally open contacts 112, 114, 116, 118 and 120 that are closed when the elevation is in service. For the sake of clarity the respective elevation feedback circuit relay contacts are suffixed in FIGS. 6 and 7 with a Roman numeral indicating the burner elevation whose operation is responsible for the actuation of the contact. By means of the circuitry employed on the counting circuit portions of the master control circuits 94 and 96 an electric current will pass, in the case of circuit 94, only when there is any one elevation in service and any two not in service and in the case of circuit 96 when there are any two elevations in service and any one not in service. Connected in series for operation in the circuit 94 is a relay 122 having normally open contacts 124, 126, 128 and associated therewith. Contacts 124, 126 and 128 are associated with other circuits in the system to be explained hereinafter and contact 130 serves to actuate a time delay relay 132 having a time delay period of two seconds after it has been energized after which its associated normally closed contacts 134, 136 and 138 are set to open. Circuit 96 is similarly constructed with relay 140 and its associated normally open contacts 142, 144, 146 and 148, the latter of which actuates a two second time delay relay 150 that opens its associated normally closed contacts 152, 154 and 156. By means of the coaction between relays 122 and 132 in master control circuit 94 and relays 140 and 150 in master control circuit 96 there is produced a pulse of two second duration that is transmitted to the various burner elevations as described hereinafter to be accepted or rejected and if accepted by an elevation to initiate startup of the burners thereof.

The elevation selection control circuit (FIG. 8) functions to determine which elevation will be added to service after the master control circuit determines that the need for an additional burner elevation is present. The elevation selection control circuit comprises sub-circuits associated with each burner elevation which, in the disclosed arrangement, are three in number, one for each elevation. Sub-circuit 158 is associated with elevation I and includes three lines, the completion of any one of which will affect actuation of the relay 160-I and latch-in relay 162-1. Relay 160-1 effects closure of contact 164-I which actuates a timing device 210 which is capable of placing each of the burners 42 of an elevation in service in a predetermined sequence. Latch-in relay 162-1 effects closure of contact 166-I which arm the burner counting circuit (FIG. 10) for each elevation. Sub-circuit 158 comprises three parallelly connected lines 168, 170 and 172 connected in series with line 174. Line 174 contains serially connected, normally closed contacts 110-1, 176-1 and 178-1 that form a permissive logic of the sub-circuit. Contact 110-1 is a normally closed contact associated with relay 102 (FIG. 11), the closure of which indicates that this elevation is not presently in service. Contact 176-1 is a normally closed contact associated with relay 180 (FIG. the closure of which indicates there has been no automatic lock-out of this elevation. Contact 178-1 is associated with a selector switch (not shown) located on the control board that is actuated by the boiler operator when it is desired to lock out an elevation from service for maintenance purposes. Each selector switch with which contact 178 is associated also contains normally open contact 182 that will be closed when contact 178 is open. As shown in FIG. 8, the panallel portion of line 170 contains contacts 182-1I and 182-111, respectively, which are associated with selector switches that pertain to elevations II and III. Lines 168, 170 and 172 of the sub-circuit contain the selection logic contacts for actuation of the relay 160-I. Line 168 contains serially connected, normally open contacts 184 and 186-I. Contact 184 is associated with another control board selector switch (not shown) that is operated to select the mode of operation of the control system, either manual or automatic. Thus contact 184 is arranged to close when the boiler operator desires to operate each elevation manually from the con trol board. Its companion contact 98 is arranged to close when automatic operation of the unit is desired. With the selector switch being in a position whereby contact 184 is closed the operator must momentarily close the contacts 186 associated with each elevation when it is desired to place the respective elevations in service. Line 170 contains the pulse generating contacts 124 and 134 operated by relays 122 and 132 in the master control circuit 94 of FIG. 6. Connected in series with these contacts are the series-parallelly connected contacts 118, 182 and 186 associated with elevations II and III. Contact 118 is a normally open contact associated with the relay 102 in each elevation feedback circuit of FIG. 11. The contacts 118-11 or 118-111 when closed indicate that the respective elevation with which they are associated is in service. Contact 186 is a normally open contact associated with the relay 180 in each burner counting circuit (FIG. 10). The contacts 186-11 or 186-111 when closed indicate that the respective elevation with which they are associated have been automatically removed from service because an elevation malfunction has been recorded by the burner counting circuit.

Line 172 contains the serially connected pulse generating contacts 142 and 152 associated with the relays 140 and 150 in the master control circuit 96 of FIG. 7. Relay 162-1 is a latch-in relay that is connected in parallel with relay 160-1 such that it is operated simultaneously therewith. This relay is elfective to close contact 166-1 and thereby arm the burner counting circuit (FIG. 10) of this elevation. The relay will remain actuated until contact 188 is closed as when a shutdown of the elevation occurs for any of the following reasons: an emergency boiler trip occasioned by the detection of a dangerous furnace condition, an elevation malfunction is determined by the burner counting circuit (FIG. 10), or a normal shutdown of the elevation is effected by a reduction in load demand which can be effected either manually or automatically. Closure of this contact will unlatch relay 162-1 to open contact 166 and thereby disarm the burner counting circuit associated with elevation I.

Subcircuit 190 is associated with burner elevation II and includes two lines 192 and 194, the completion of any one of which will effect actuation of the relays 160-II and 162-11 for closing contacts 164-11 and 166-II in a similar manner and for a similar purpose as the relays 160-1 and 162-1 of elevation I as described above. Line 196 contains contacts 110-11, 176-11 and 178-II that are the counterparts of contacts 110-1, 176-1 and 178-1 and comprise the permissive logic of the subcircuit. Line 192 contains the same normally closed contact 184 that is closed when the vapor generator is set for manual operation in series with contact 186-II that is momentarily closed by the boiler operator when it is desired to place elevation II in service. Line 194 contains, in parallel, the pulse generating contacts 126 and 136 that are actuated by the relays 122 and 132 in the master control circuit 94 and the pulse generating contacts 144 and 154 that are actuated by the relays 140 and 150 in the master control circuit 96. Contact 188-11 is the counterpart of the contact 188-1- and is closed when elevation II is to be shut down in the same manner as described for elevation I above.

Subcircuit 198 is associated with elevation III and includes three lines 200, 202 and 204, the completion of any one of which will effect actuation of the relays 160-111 and 162-111 for closing the contacts 164-111 and 166-111 similar to the closing of the comparable relays in elevations I and II described above. Line 200 contains serially connected contacts 184 and 186-111 which are closed when it is desired to initiate an elevation st'artup manually. Line 202 contains the pulse generating contacts 128 and 138 connected in series with parallelly connected contacts 120-11, 208-11 and 182-11. Contact 120-1I is associated With relay 102 in the elevation feedback circuit (FIG. 11) and is closed when elevation 11 is in service. Contact 208- II is associated with relay 180 in the burner counting circuit (FIG. 10) and is closed when elevation 11 has been automatically removed from service because of equipment malfunction as indicated by its associated burner counting circuit. Contact 182-11 is that contact which is closed when elevation 11 has been manually locked out of service by the operators opening contact 178-11. Line 204 contains the serially connected pulse generating contacts 146 and 156 associated with master control circuit 96.

In FIG. 9 there is shown a timer 210 that is typical of that employed for sequencing each of the burners of an elevation into service. Obviously, since there are three elevations in the vapor generator described herein, there will be three such timers employed in the system, one for each of the elevations I, II and III. The timer 210 is of the synchronous motor driven cam actuating type that normally remains in the timed-out position. Momentary closure of its control contact 164 resets the timer to zero and opening the contact initiates the timing operation which may be of two minute duration. Each timer 210 is arranged to actuate seven normally open contacts to their closed position in timed sequence so as to sequentially effect actuation of the various burners and control elements in each elevation. As shown, the timer first closes contact 92 that is associated with all of the igniters 44 in the elevation. This contact remains closed for five seconds and there-after the contact 88 associated with each of four burner pairs, A-G, C-E, B-F and D-H are closed to open the fuel valve 74 associated with each burner 42. After the last burner pair contact 88 has been closed, the .contact 212 is closed. Closure of this contact 212 eifects actuation of the respective burner counting circuit of FIG. 10. Lastly, contact 214 in the elevation feedback circuit of FIG. 11 is closed which will actuate relay 102 as long as contact 216 is closed indicating that relay 180 has not been actuated and therefore there is no equipment defect in the burner elevation.

The burner counting circuit shown in FIG. 10 is one of three such counting circuits employed in the system,

one being used with each burner elevation. For the sake of brevity, only one such circuit is described. As shown, the circuit comprises contacts 166 and 212 connected in series with the parallelly connected contacts 82, 84 and 86 associated with their respective burners 42. The contacts 82, 84 and 86 are normally closed and are arranged to open when the burner fuel valves 74 associated with the respective burners 42 reach their full open position at which time contact 76 is closed and relay actuated thereby opening the contacts 82, 84 and 86. The numerals delineating the contacts in FIGURE 10 are suflixed by an appropriate letter to indicate the furnace corner with which each contact is associated. The parallel arrangement of the contacts 82, 84 and 86 is such that the circuit cannot be complete as long as at least three out of four burners 42 in each furnace cavity 22 and 24 are in operation. If, on the other hand, less than three burners in either furnace cavity are operable, as indicated by the opening or failure to open of the associated fuel valves 74, the relay 180 will be actuated closing contacts 90, 186 and 208 and opening contacts 176 and 216. Contacts 186 and 208 are those contained in the elevation selection control circuit of FIG. 8 for determining which of the burner elevations is capable of being placed in service when the need for such arises. Contact 176 is likewise operative in the elevation selection control circuit, being located in lines 174, 196 and 206 as part of the permissive control logic. Contact 216 is operative in the elevation feedback circuit (FIG. 11) to prevent actuation of relay 102 when relay 180 is actuated. Relay 180 is a latch-in relay which must be reset by closure of contact 220 by the boiler operator after the condition which effected actuation of relay 180 has been removed by repair or replacement of the defective burner part.

In FIG. 11 is shown a typical elevation feedback circuit, there being three in number, one associated with each burner elevation. The circuit contains normally open contacts 214 and normally closed contacts 216 connected in series with relay 102. The relay 102 has associated therewith four normally closed contacts 104, 106, 108 and 110 and five normally open contacts 112, 114, 116, 118 and 120. It is set to be actuated when the elevation with which it is associated has been placed in service. Contacts 104, 106, 108, 112, 114 and 116 are those contained in the master control circuits 94 and 96 of FIGS. 6 and 7 while contacts 110, 118 and 120 are those contained in the elevation selection control circuit of FIG. 8. It is the function of this circuit to transmit feedback signals to the master control circuits and the elevation selection control circuit indicating whether or not the burner elevation with which it is associated has been placed in service.

The operation of the herein-disclosed system is as follows. Vaporizable liquid is admitted to the tubes 26 in the vapor generator 12. Thereafter contact 186-1 in line 168 of the elevation selection control circuit is closed with the intention of placing elevation I of the burner system in service, contact 184 having previously been closed by the operator indicating that manual rather than automatic startup of the elevation was desired. Ignition of the burners 42 in elevation I will proceed as long as contacts 110-I, 176-1 and 178-1 are closed to permit electric current to pass through the circuit to energize the coil of relay 160-I. Contact 110-I will be closed as long as this elevation is not already in service as determined by actuation of relay 102 in the elevation feedback circuit (FIG. 11) associated with this elevation. Contact 176-I will be closed as long as there is no malfunction in the burner system as determined by actuation of latch-in relay 180 in the burner counting circuit (FIG. associated with elevation I. Contact 178-I will be closed as long as elevation I has not manually been locked out for maintenance as indicated by a selector switch (not shown) associated with this contact. Thus, with all of the aforementioned contacts being closed electric current is permitted to pass to the coil of relay 160-I actuating the relay to close contact 164-I. Closure of contact 164-1 serves to reset the timer 210 associated with elevation I. Once the switch associated with contact 186-1 is removed from its closed position, it being held closed by the operator only momentarily, the timer 210 begins effecting closure in timed sequence of the respective contacts 88, 92, 212 and 214 with which it is associated. Closure of contacts 92 serves to establish a flame in all of the igniters 44 in elevation I. Thereafter the four pairs of burners 42, one burner in each furnace cavity, are put in service by actuating the contacts 88 to open the fuel valves 74 associated with each of the burners. The burners are arranged to be placed in operation in the following paired sequence. First the burners in corners A and G are put in service, next corners C-E, then corners B-F, and finally corners D-H. Simultaneously with the actuation of relay 164-1, relay 166-1 is latched to close contact 166-1 arming the burner counting circuit (FIG. 10) for elevation I. As each of the burner valves 74 in elevation I reach their open position contact 76 is closed actuating relay 80 to open the contacts 82, 84 and 86 of the burner counting circuit. After a period of time (90 seconds) during which all of the burners 42 of elevation I should have been placed in service contact 212 in the burner counting circuit is closed by the timer 210 to render the counting circuit operative. If at least three out of four burners in each furnace cavity 22 and 24 are operating no current will be permitted to pass through the counting circuit to actuate latch-in relay 180. If, however, less than three out of the four burners in either furnace cavity are ignited the relay 180 will be actuated to close contacts 186, 208 and 90 and open contacts 176 and 216. Actuation of contact 90 serves to automatically shut down those burners in the elevation that did ignite as by effecting closure of the valves 74 by actuating the valve operators to close the valves which terminates fuel flow to the respective burners. It will be assumed however for this description that the burners 42 in elevation I functioned properly and are therefore in operation. Because the elevation is in service relay 102 in the elevation feedback circuit (FIG. 11) associated with elevation I is actuated by the closure of contact 214 of timer 210. When this occurs contacts 112, 114, 116, 118 and 120 are closed and contacts 104, 106, 108 and opened in the respective master control circuits 94 and 96 (FIGS. 6 and 7) and the elevation selection control circuit (FIG. 8).

With reference now to FIGURES 1, 3 and 5, as the load demand on the vapor generator 12 increases the output control 16 effects gradual opening of the regulator valve 38 to increase the supply of vapor to the turbine 14. This is reflected as a lowering of the pressure in vapor line 36 which is sensed by the sensor 40 to operate the controllers 18 and 20 which effect an increase in the fuel flow in supply line 46 by operation of the main fuel regulator valve 54. When the pressure in line 46 reaches 800 p.s.i. which has been determined as the point just below maximum output for eight burners the pressure switch associated with sensor 62 closes actuating contacts 66 in the master control circuit 94. This circuit 94, havint, been rendered operable by the operator having previously actuated the selector switch to close contact 98 thereby indicating a desire for automatic control of the system, is thus placed in service. Now, with elevation I in operation and elevations II and III not in operation an electric circuit path is completed through contacts 106-III, 106-II and 112-I, contact 112-1 having been closed by relay 102 when the elevation was proved to be in service and contacts 106-III and 106-II being normally closed contacts on similar relays 102 in their respective elevation feedback circuits. Completion of this circuit path effects a coaction of relays 122 and 132 to produce a pulse of two seconds duration that is transmitted to the elevation selection control circuit (FIG. 8) by closure of the contacts 124, 126 and 128, with contacts 134, 136 and 138 remaining closed for two seconds before opening thereby producing a pulse. Elevation III cannot accept this pulse because the relay 102 associated with the elevation feedback circuit of elevation II has not actuated, thereby contact -II remains open signifying that elevation II is not in service. Also, contacts 208-II and 182-II in line 202 are open indicating that elevation II is not locked out of service. With contacts 126 and 136 closed, however, a circuit path is completed for two seconds through lines 194 and 196 to actuate relays -II and 162-II closing contacts 164-II and 166-II. Contacts 110-II, 176-II and 178-II are already closed because this elevation is not in service, and it has been neither manually or automatically locked out of service. Closure of contact 164-II actuates the timer 210 associated with elevation II and its startup proceeds according to the timed sequence referred to above until its completion whereupon relay 102 in the elevation feedback circuit associated with elevation II is actuated to close contacts 112, 114, 116, 118 and 120 and open contacts 104, 106, 108 and 110 in the master control circuits 94 and 96 and the elevation selection circuit (FIG. 8). Closure of contact 166-1 arms its associated burner counting circuit, and closure of contact 212 off the timer 210 places the counting circuit in service. Because the burners 42 in elevation II operated satisfactorily the burner counting circuit for the elevation was rendered ineffective and relay 180 did not actuate therefore contact 216 in the elevation feedback circuit remained closed.

Assuming, however, that elevation II was not available for service because of one of several reasons, namely it, not elevation I, was the first placed in service, or it was locked out for maintenance either automatically or manually, one of the contacts 110-II, 176-II or 178-II would be open thereby preventing actuation of the relays 164-II and 166-II when contacts 126 and 136 produced the pulse. In this case one of the contacts 120-II, 208-II or 182-II in line 202 of the elevation III portion of the elevation selection control circuit would be closed so that elevation III would accept the pulse produced by the actuation of contacts 128 and 138 simultaneously with contacts 126 and 136 in line 194. Contacts 120-II, 208- II or 182-II are always closed when the contacts 110-II, 17 6-II or 178-11 respectively are opened (see FIGS, 10 and 11). Elevation III will be placed in operation as long as its contacts 110-III, 176-III and I78-III in line 206 are closed indicating it is capable of being placed in service in which case relays 160-III and 162-III will be actuated. Actuation of relay 160-III would start the timer 210 and actuation of relay 162-III would arm the burner counting circuit for elevation III. Startup of this elevation would then proceed in the same mannner as that described above with relation to elevations I and II.

The herein-disclosed control system is arranged so that should elevation I not be available for startup at the first instance then elevation II can be manually placed in service by closure of contacts 184 and 186-II in the same manner as was explained with regard to the startup of elevation I above. Thereafter, the system will seek to place elevation III in service as the second elevation and, if elevation III is not available for service, then elevation I can accept the startup pulse as the alternate, it being assumed that the condition that prevented its initial startup had been rectified. Therefore with elevation II, being the first elevation placed in service, and elevation III not being available for service, contact 186-III in line 170 of the elevation I portion of the elevation selection control circuit is closed, elevation IIIs relay 180 (FIG. 10) having been actuated indicating that the elevation has been automatically locked out, contact 118-II is closed because elevation IIs relay 102 (FIG. 11) has been actiiated indicating that this elevation is in service. Thus, with contacts 110-I, 176-1 and 178-1 being closed indicating that elevation I is available for service the pulse generated by the coaction of relays 122 and 132 in the master control circuit will actuate the contacts 124 and 134 thereby actuating the relays 160-1 and 162-1 so that startup of this elevation will occur in the same manner as explained above for the other elevations. Were elevation III to have been manually locked out of service contact 182-III in line 170 would be closed instead of contact 186-III but the procedure would thereafter continue in the same way.

If, for some reason, elevation III were the first to be placed in service, the system is arranged to place elevation II in service second in the same manner explained above. However, should elevation II not be available then elevation I can be placed in service as the alternate since 10 contact 186-II or contact 182-II would be closed indicating that elevation II has been locked out of service and contact 118-III would be closed indicating that elevation III was already in service. Thereafter the startup procedure would continue in the same manner as explained above.

One important feature of the present control system is that it is capable of automatically rectifying a situation Where the startup of the second elevation is begun but during the process of its starting up it is determined that less than three of its four burners in either furnace cavity are functioning properly and the elevation must be shut down. In such case a startup pulse will be thereafter passed to the third elevation. This can be explained by assuming that elevation I is in service, that the load demand on the unit increased to the point where the pressure in the main fuel line 46 was raised to 800 p.s.i. and that elevation II was initially regarded as being capable of being placed in service since contacts -II, 176-II and 178-II were closed. In such case relays 160-II and 162-11 would close actuating the timer 210 associated with elevation II to proceed with the ignition of the several burner pairs in elevation II. After contact 212 of the timer closed and the burner counting circuit of this elevation was placed in service, electric current was permitted to pass through the counting circuit to actuate the latch-in relay 180 since less than the minimum number of burners in elevation II were put in service. Actuation of relay 180 would immediately close all the burner valves 74 in elevation II by closing the contact 90 thereby removing all of the burners from service. When this occurs the pressure in the main fuel line, which had dropped below 800 p.s.i. when some of the supply valves 74 of the burners 42 in elevation II opened, would immediately rise again to 800 p.s.i. or above thereby again closing contact 66 in the master control circuit 94 which had opened when the pressure fell below 800 p.s.i. When contact 66 again closes another pulse is generated by the actuation of relays 122 and 132 but this time only elevation III can accept the pulse since elevation II has now been locked out by actuation of its relay 180 which can only be reset by closure of contact 220 after the condition that caused the elevation to be removed from service is rectified. Startup of elevation III will then proceed in the same manner as explained hereinbefore. This procedure will occur no matter which elevation is in operation and which elevation malfunctions during the process of its startup. A pulse will again occur that is capable of being accepted by the third elevation.

All of the foregoing explanation has been directed to the operation of the present control system in instances where there has been one elevation in service and it is desired to place a second elevation in service. The explanation covered all possible contingencies. The following explains the operation of the system when two elevations are in service and it is desired to place the third in service. When such occurs, the system control shifts from master control circuit 94 (FIG. 6) to master control circuit 96 (FIG. 7). This circuit, by means of its counting portion, determines that two elevations are in service and one elevation is not in service by a combination of contacts 106, 108, 114 and 116 as shown in the figure. When two elevations are in service the minimum main fuel line pressure will be point b as shown in FIG. 5 or approximately 170 p.s.i. since there are then sixteen fuel burners 42 in service. Thereafter, increases in load demand will increase the fuel pressure to point 0 or 485 p.s.i which has been determined as the pressure at which the remaining elevation of burners should be placed in service. When the pressure in fuel line 46 reaches 485 p.s.i. the contact 68 of the pressure switch associated with pressure sensor 64 closes. This now effects actuation of relays and of master control circuit 96 to produce a twosecond pulse in the same manner as one is produced by relays 122 and 132 in master control circuit 94 by closing contacts 142, 144 and 146 and opening contacts 152, 154

and 156 two seconds later. The pulse is transmitted to each of the portions 158 and 190 and 198 of the elevation selection control circuit (FIG. 8) in lines 172, 194 and 204, respectively. The elevation, either I, II or III, to accept the pulse will simply be that elevation that is not already in service, or the only elevation whose contact 110 is closed. The pulse is passed to the relays 160 and 162 of that elevation and startup thereof proceeds in the same manner as explained hereinbefore.

By means of the present invention, therefore, there is provided means for automating the operation of a large capacity vapor generator having a multiplicity of burners and their associated equipment throughout the complete load range of the unit. As can be seen, the instant control system employs relatively few operating elements in an uncomplicated arrangement. However, the system is capable of safely and effectively initiating startup of the burners of the vapor generator during the occasion of all contigencies that could occur during the operation of the unit.

What is claimed is:

1. In a power plant including a vapor generator having a furnace chamber, a burner system including a plurality of fuel burners arranged in groups positioned at spaced locations in said furnace chamber and burner operating means associated with each of said fuel burners, a burner control system operated in response to load increases on said power plant including: means for sensing an increased load demand on said power plant and for emitting a signal in response thereto; burner monitor means for determining which of said burner groups are capable of being placed in operation; means rendering those burner groups not capable of being placed in service ineffective to receive said signal; and means for transmitting said signal to the operators of the burner group capable of being placed in service for starting up said operable burner group to satisfy said increase in load demand.

2. In a power plant including a vapor generator having a furnace chamber, a burner system including a plurality of fuel burners arranged in groups positioned at spaced locations in said furnace chamber and burner operating means associated with each of said fuel burners, a burner control system operated in response to load increases on said power plant including: means for sensing an increased load demand on said power plant and for emitting a signal in response thereto; burner monitor means for determining which burner group is in service and which of the remaining burner groups is capable of being placed in service; means for rendering those burner groups not capable of being placed in service ineffective to receive said signal and means for transmitting said signal to the operators of the said burner group that is capable of being placed in service for starting up said burner group to satisfy said increase in load demand.

3. In a power plant including a vapor generator having a furnace chamber, a burner system including a plurality of fuel burners arranged in groups positioned at spaced locations in said furnace chamber and burner operating means associated with each of said fuel burners, a burner control system operated in response to load increases on said power plant including: means for sensing an increased load demand on said power plant and for emitting a signal in response thereto; first circuit means adapted to register the number of burner groups in operation and for transmitting said signal in the form of a pulse when a predetermined number of burner groups are in operation; second circuit means for determining the capability of each burner group to be placed in service, said second circuit means including means for rendering those burner groups not capable of being placed in service ineffective to receive said pulse and means for transmitting said pulse to the operators of the burners in the burner group capable of being placed in service for starting up said burner group to satisfy said load demand increase.

4. In a power plant including a vapor generator having a furnace chamber, a burner system including a plurality of fuel burners arranged in groups positioned at spaced locations in said furnace chamber and burner operating means associated with each of said fuel burners, a burner control system operated in response to load increases on said power plant including: means for sensing an increased load demand on said power plant and for emitting a signal in response thereto; first circuit means adapted to register the number of burner groups in operation and for transmitting said signal in the form of a pulse when a predetermined number of burner groups are in operation; second circuit means for determining the capability of each burner group to be placed in service and for routing said pulse to each said capable burner group in a predetermined sequence to place one of said burner groups in service, and means for generating a second pulse to be routed through said second circuit means to another said capable burner group when the burners of said one burner group fail to be placed in service.

5. In a power plant including a vapor generator having a furnace chamber, a burner system including a plurality of fuel burners arranged in groups positioned at spaced locations in said furnace chamber and burner operating means associated with each of said fuel burners, a burner control system operated in response to load increases on said power plant including: means for sensing an increased load demand on said power plant and for emitting a signal in response thereto; first circuit means adapted to register the number of burner groups in operation and for transmitting said signal in the form of a pulse when a predetermined number of burner groups are in operation; second circuit means for determining the capability of each burner group to be placed in service and for routing said pulse to all of said capable burner groups, said second circuit means including means for rendering only one of said burner groups capable of receiving said pulse and means rendering another of said burner groups capable to receive said pulse should said one burner group fail to be placed in service.

6. In a power plant including a vapor generator having a furnace chamber, a burner system operable in said furnace chamber comprising fuel burners arranged at spaced elevations of said furnace chamber and pulse-actuated burner operators associated with each of said fuel burners, a burner control system operable when at least one of said burner elevations is in service for starting up additional elevations of burners in response to load increases on said power plant, said burner control system comprising: means for sensing an increased load demand on said power plant and for emitting a signal in response thereto; first circuit means containing contacts operated in response to the operation of the various burner elevations for determining the state of operation of each and for transmitting said signal in the form of a pulse when a predetermined number of burner elevations are in service; second circuit means containing contacts operated in response to the state of operation of the fuel valves associated with said burners, said second circuit nieans including subcircuits for controlling the operation of each elevation and each subcircuit cointaining first contact means adapted to close when the associated burner elevation is capable of being placed in service and second contact means for transmitting said pulse to the burner operators of one of said burner elevations and the subcircuits associated with all but one of said burner elevations containing third contact means adapted to register the state of operation of the other burner elevations whereby said pulse will be directed to the burner operators of each of said burner elevations in a predetermined sequence.

7. The arrangement of claim 6 including burner counting circuit means containing contacts operated in response to the operation of the burners in each burner elevation for determining the failure of the respective burner elevations to be placed in service and for emitting a signal in 13 response thereto and means for transmitting said signal to said second circuit means.

8. The arrangement of claim 7 including means for transmitting said burner counting circuit signals to operate said first and third contact means in said second circuit means.

9. The arrangement of claim 7 including means for transmitting the signal emitted by said burner counting circuit to the operators of all of the burners in the associated elevation to discontinue the operation of said burners.

10. The arrangement of claim 8 including a relay actuated in response to the failure of a predetermined number of burners to be placed in service, said relay effecting the closure of contacts included in said third contact means and opening contact included in said first contact means.

11. The arrangement of claim 7 including means for arming the burner counting circuit means immediately upon transmission of said pulse to the burner operators of a burner elevation and means for rendering said burner counting circuit means effective only after sufiicient time has elapsed for all burners in said burner elevation to be placed in service.

12. In a power plant including a vapor generator having a furnace chamber, a burner system operable in said furnace chamber comprising a plurality of fuel burners arranged in groups located at a minimum of three elevations of said furnace chamber, fuel supply valves associated with each of said burners, electric pulse-actuated operators for operating each of said fuel supply valves to place the burners in service and a burner control system operable when at least one of said burner elevations are in service for starting up additional burner elevations in response to load increases on said power plant, said burner control system including: means for sensing an increased load demand on said power plant and for emitting a signal in response thereto; master control circuit means including an arrangement of electrical contacts for determining the number of burner elevations in service and the number of burner elevations not in service; said master control circuit means also including means for receiving said load increase signal and for transmitting said signal in the form of an electric pulse; burner elevation selection control circuit means including a plurality of subcircuits each associated with one burner elevation and each being adapted to receive said pulse, said subcircuits comprising a first group of contacts operable when the associated burner elevation is capable of being placed in service and contact means operable to transmit said pulse to the valve operators of the burners in its associated burner elevation, a second group of contacts in all but one of said subcircuits operable to determine th operability of the remaining burner elevations whereby said pulse will be directed to all of said subcircuits but will be transmitted to the valve operators by the pulse transmitting contacts of only one of said subcircuits.

13. The arrangement of claim 12 wherein said master control circuit operates relay means operable to actuate contacts in the subcircuits of said elevation selection con-' trol circuit.

14. The arrangement of claim 13 wherein said relay means includes a time delay relay having normally closed contacts associated therewith which are opened upon actuation of said time delay relay thereby producing said pulse.

15. The arrangement of of claim 12 including a burner counting circuit associated with each of said burner elevations containing contacts operable in response to the opening of said fuel supply valves and latch-in relay means operated by said burner counting circuit contacts actuable when a predetermined number of fuel supply valves fail to open, said latch-in relay having normally closed contacts associated with said first group of contacts and normally open contacts associated with said second group of contacts.

16. The arrangement of claim '15 including means for arming said burner counting circuit immediately upon transmission of said pulse to the fuel valve operators in a burner elevation and means for rendering said burner counting circuit effective only after suflicient time has elapsed for all the burners in the associated burner elevation to be placed in service.

17. The arrangement of claim 16 including elevation feedback circuit means associated with each of said burner elevations containing normally closed contacts operable in the first group of contacts in the elevation sequence control subcircuit of its associated burner elevation and second normally open contacts operable in the second group of contacts in the elevation sequence control subcircuit associated with the other burner elevations, feedback circuit relay means for operating said feedback circuit contacts, and means for actuating said feedback circuit relay means when the associated burner elevation is placed in service.

18. The arrangement of claim 17 wherein said means for actuating said feedback circuit relay means comprises a normally closed contact operated by said burner counting circuit latch-in relay.

19. The arrangement of claim 18 including means for rendering said elevation feedback circuit means effective only after sufficient time has elapsed for all of the burners in the associated burner elevation to be placed in service.

20. The arrangement of claim 15 wherein said latch-in relay also has contacts operably connected to the associated fuel valve operators to close said valve upon actuation of said latch-in relay.

21. The arrangement of claim 20 including means for actuating said master control circuit to produce a second pulse after actuation of said latch-in relay.

22. In combination with a vapor generator having a furnace chamber, a burner system operable in said furnace chamber including a plurality of fuel burners arranged in groups located in three elevations of said furnace chamber, a fuel line supply fuel to said burners, fuel supply valves in said fuel line operatively associated with each of said burners, electric pulse-actuated operators for operating each of said valves to place said burners in service, and a burner control system operable when at least one of said burner elevations are in service for starting up additional elevations in response to increased load demand on said vapor generator, said burner control system including: means for sensing an increased load demand on said vapor generator comprising pressure switch means actuable to produce a signal upon sensing a predetermined pressure in said fuel line; master control circuit means including a series-parallel arrangement of electrical contacts actuable to determine the number of burner elevations in service and the number of burner elevations not in service, said master control circuit means including a contact actuable by said pressure switch and means for transmitting said signal in the form of an electric pulse; burner elevation selection control circuit means including three subcircuits each associated with one of said burner elevations, said subcircuits each comprising a first group of serially connected contacts operable when the associated burner elevation is capable of being placed in service and contact means operated by said master control circuit pulse transmitting means to receive said pulse, a second group of contacts associated with each of two of said subcircuits operable to determine the operability of the respective burner elevations, said second group of contacts in the subcircuit associated with the first of said burner elevations including contact means arranged to pass an electric current when either the second or third of said burner elevations are not available for service and the second group of contacts in the subcircuit associated with the third of said burner elevations 15 including contact means arranged to pass an electric current when said second burner elevation is not available for service and relay means operatively connected to each of said subcircuits for transmitting said pulse to the fuel valve operators associaeed with only one of said burner elevations.

23. The arrangement of claim 22 including a burner counting circuit associated with each of said burner elevations containing contacts operable in response to the opening of said fuel supply valves and a latch-in relay operated by said burner counting circuit contacts actu able when a predetermined number of fuel supply valves fail to open, said latch-in relay having normally closed contacts operable in said first group of contacts in the mutually associated subcircuit and normally open contacts operable in the second group of contacts in the su-bcircuits associated with the other burner elevations.

24. The arrangement of claim 23 including means for arming said burner counting circuits immediately upon transmission of said pulse to the fuel operators in the associated burner elevation and means for rendering said burner counting circuit effective only after sufficient time has elapsed for all the burners in said associated burner elevation to be placed in service.

25. The arrangement of claim 23 wherein said latchin relay also has contacts operably connected to the associated fuel valve operators to close said valves upon actuation of said latch-in relay.

26. The arrangement of claim 25 including means for actuating said master control circuit to produce a second pulse after actuation of said latch-in relay.

27. The arrangement of claim 24 including elevation feedback circuit means associated with each of said burner elevations containing normally closed contacts operable in the first group of contacts in the elevation sequence control subcircuit of its associated burner elevation and second normally open contacts operable in the second group of contacts in the elevation sequence control subcircuit associated with the other burner elevations, feedback circuit relay means for operating said feedback circuit contacts, and means for actuating said feedback circuit relay means when the associated burner elevation is placed in service.

28. The arrangement of claim 27 wherein said means for actuating said feedback circuit relay means comprises a normally closed contact operated by said burner counting circuit latch-in relay.

29. The arrangement of claim 28 including means for rendering said elevation feedback circuit means effective only after sufficient time has elapsed for all of the burners in the associated burner elevation to be placed in service.

30. A method of controlling the addition of heat to a vapor generator in response to increasing load demand, said vapor generator having a burner system including a plurality of burner units, fuel valves controlling the supply of fuel to said burner units and electric pulse-actuated operators for operating said valves, the steps comprising: placing one of said burner units in service; sensing the load demand on said vapor generator and regulating the operation of said operating burner unit in response thereto; at a predetermined magnitude of load demand corresponding substantially to the maximum output of said operating burner unit indicating the need for increased burner output by emitting a signal; transforming said signal to an electric pulse; transmitting said pulse to all of the burner units not operating; sensing the operational availability of all of said burner units; selecting one of said burner units to receive said pulse in response to a predetermined sequence and burner unit availability; and passing said pulse to the valve operators of said soselected burner unit.

31. The method as recited in claim '30 including the steps of: sensing the startup of said so-selected burner unit, and reestablishing said signal should said so-selected burner unit fail to be placed in service.

32. A method of controlling the addition of heat to a vapor generator in response to increasing load demand, said vapor generator having a burner system including at least three burner elevations, a plurality of burners located in each elevation, a fuel supply line, fuel valves controlling the supply of fuel to said burners and electric pulse-actuated operators for operating said valves, the steps comprising: placing one of said burner elevations in service; measuring the pressure in said fuel supply line to determine the load demand on said vapor generator and regulating the operation of the burners in said operating burner elevation in response thereto; at a predetermined magnitude of fuel supply line pressure corresponding substantially to the maximum output of said operating burners emitting a signal; transforming said signal to an electric pulse; sensing the operational availability of all of said burner elevations; selecting one of the remaining burner elevations to receive said pulse in response to a predetermined sequence and operational availability passing said pulse to the valve operators of said so-selected burner elevation.

33. The method as recited in claim 32 including the steps of: sensing the operation of the burners in said soselected burner elevation after the period of time of placing all of the burners in said elevation in service has elapsed, and reestablishing said signal should said soselected burner elavation fail to be satisfactorily placed in service.

34. The method as recited in claim 33 wherein sensing the operation of the burners in said so-selected burner elevation is accomplished by counting the number of fuel valves that have opened; closing all of the valves in said so-selected burner elevation to permit the pressure in said fuel supply line to rise again to said predetermined magnitude.

References Cited UNITED STATES PATENTS 2,403,230 7/1946 Nagel et al 236-26 X 2,519,240 8/ 1950 Fellows 23626 X 2,540,778 2/ 1951 Dickey 23626 3,045,744 7/ 1962 Tjernlund.

EDWARD J. MICHAEL, Primary Examiner. 

1. IN A POWER PLANT INCLUDING A VAPOR GENERATOR HAVING A FURNACE CHAMBER, A BURNER SYSTEM INCLUDING A PLURALITY OF FUEL BURNERS ARRANGED IN GROUPS POSITIONED AT SPACED LOCATIONS IN SAID FURNACE CHAMBER AND BURNER OPERATING MEANS ASSOCIATED WITH EACH OF SAID FUEL BURNERS, A BURNER CONTROL SYSTEM OPERATED IN RESPONSE TO LOAD INCREASES ON SAID POWER PLANT INCLUDING: MEANS FOR SENSING AN INCREASED LOAD DEMAND ON SAID POWER PLANT AND FOR EMITTING A SIGNAL IN RESPONSE THERETO; BURNER MONITOR MEANS FOR DETERMINING WHICH OF SAID BURNER GROUPS ARE CAPABLE OF BEING PLACED IN OPERATION; MEANS RENDERING THOSE BURNER GROUPS NOT CAPABLE OF BEING PLACED IN SERVICE INEFFECTIVE TO RECEIVE SAID SIGNAL; AND MEANS FOR TRANSMITTING SAID SIGNAL TO THE OPERATORS OF THE BURNER GROUP CAPABLE OF BEING PLACED IN SERVICE FOR STATING UP SAID OPERABLE BURNER GROUP TO SATISFY SAID INCREASE IN LOAD DEMND. 